1. Field of the Invention
The present invention generally relates to an apparatus and method for producing a composite material having a predetermined surface characteristic formed thereon. More particularly, the present invention relates to an apparatus and method for producing a rigid composite material sheet or a flexible web having at least one patterned relief surface of high quality and definition which is particularly useful for producing high quality optical components such as lenticular sheets and/or webs for use with pictures and photographs.
2. Description of the Related Art
In the commercial industry, it is often desirable to impart visual effects such as three dimensionality or motion characteristics upon packages or labels of consumable products and the like. Due to expense and ease of design, regular print advertising was the pre-eminent and preferred form used on consumables. Regular print advertising is accomplished by printing, two-dimensional, non-movable information using words and pictures on packaging, labels, billboards, signs and the like. While some conventional print advertisements and packaging are interesting, most are not. Thus, consumers' attention is not attracted to the fullest extent possible. To obviate this problem, the use of products having lenticular effects has become increasingly popular. A reverse printed lenticular web has the ability to attract ones attention by presenting an image that has depth, morphing characteristics, and/or can appear to have movement or the capacity to flip from one image to another. By way of example, a package or label having a printed lenticular web image on a store self has the ability to attract ones attention for a longer period of time than comparable non-lenticular packages.
Known lenticular lenses, or micro lenses, as used in imaging are typically elongated, lineal or dot patterned across an entire transparent web such that an image may be seen therethrough with the desired visual effect. The lenses can be either convex or concave in configuration. In addition, some lenses can be elliptical in shape. Typically, the lenses have a pre-determined radius of curvature and a pre-determined uniform pitch or repeat pattern. Lenticular lenses are generally thin, transparent lenses that are flat on one side and include a plurality of parallel, linear, side by side lenticules—elongate or convex lenses—on a second side. Typically, an image is printed on the flat side to create a desired visual effect of the image when viewed through the lenticules on the opposing side. The combination of the lenses and an image is referred to as a “lenticular assembly”.
Prior art lenticular assemblies are typically manufactured from a continuous thin, flexible web. Manufacture of lenses may be performed in a variety of ways. Generally, lens shapes are engraved on a precision engraving and diamond turning machines into special metal cylinders and polished to a high luster. The lenses are then index/step and repeat engraved to extremely high accuracies measured in the millionths of an inch onto the thin flexible web using an extrusion process. Thereafter, the images to be used are produced by combining or interlacing a selected image on a computer such that the image is produced in a manner ready for printing. Once interlaced, the image is reverse printed on the rear or back, planar side of the lenticular material produced. Reverse printing is accomplished by any conventional method by any conventional printing means. Subsequent to the reverse printing the lenticular assembly is complete.
By way of a specific example, U.S. Pat. No. 4,420,502 to Conley discloses an apparatus and method for producing a flexible sheet material having a predetermined surface characteristic of high quality and definition formed on one side thereof. The apparatus of the U.S. Pat. No. 4,420,502 invention comprises first and second rotating rolls which are mounted on a generally horizontally extending axis with the peripheral surfaces thereof closely spaced from one another to form a narrow gap corresponding to the desired overall thickness of the composite sheet. The second rotating roll has a peripheral surface of a predetermined texture corresponding to the desired surface characteristic to be produced in the sheet. A base web of predetermined thickness less than the narrow gap is directed onto the peripheral surface of the first roll and is advanced along an arcuate path around the periphery of the first roll and then through the narrow gap between the first and second rolls. The base web, upon passing through the narrow gap, is then directed around the second roll and along a predetermined arcuate path around the periphery thereof. A flowable uncured actinic radiation curable thermosetting resin is directed behind the narrow gap between the first and second rolls and into contact with the exposed surface of the base web so that a coating of the resin is applied to the base web and is carried with the base web through the narrow gap to this position the coating, upon emerging from the gap, beneath the base web and in contact with the peripheral surface of the second roll. Then actinic radiation is directed through the base web and onto the coating to cure and harden the coating while in contact with the patterned surface of the second roll. The base web is then directed away from the second roll to separate the cured and hardened coating from the roll and thus produce a sheet with a predetermined surface characteristic of high quality and fine definition accurately reproducing the surface texture of the second roll.
The above described methods of manufacture for lenticular material suffers a number of shortcomings. First, and most importantly, the U.S. Pat. No. 4,420,502 patent fails to teach of an apparatus and method which is useful for the production of thick, rigid lenticular sheets as well as flexible, thin carrier webs. Rather, the U.S. Pat. No. 4,420,502 patent only teaches of an apparatus useful with flexible, thin carrier webs. Noticeably too, the U.S. Pat. No. 4,420,502 patent fails to disclose a doctor blade or other device which is used to meter the coating on the engraving roll for curing and transferring the pattern to the stable carrier web.
In addition, the use of rigid lenticular sheets are rapidly becoming popular, due the need for products, such as signs and billboards, to be more stable and resistant to environmental conditions, such as inclement weather. Similar to the manufacture of the thin flexible webs, various methods of manufacture for thick, lenticular sheets exist. However, as with the thin, flexible webs, conventional methods provide material with less than accurate reproductions of the engraved, patterned roll. Moreover, less stability results from the extrusion of the sheets. For example, when a wide sheet material is desired or required, the extrusion process is undesirable as more distortion of the sheet occurs due to the fact that the product must be cooled and pulled down the line. Currently, known art fails also to provide a machine or method which serves the dual purpose of producing either a flexible material web or a rigid sheet material having a predetermined characteristic thereon operable for use with lenticular applications.
It is therefore apparent, that there exists a need for an apparatus and method capable of producing a stable patterned rigid sheet or continuous flexible thin web which does not vary in dimensions; which has a more exacting reproduction of the pattern from the engraved cylinder; and which provides the ability to produce wider patterned sheets or webs with stability and exactness; both thick rigid patterned sheets, up to ¼ inch and thin flexible patterned sheet, down to 0.001 inch or less.